Device comprising an electric discharge tube for very high frequencies and a discharge tube for use in such a device



J ly 8, 1 5 B. B. VAN IPEREN 2,842,704

DEVICE COMPRISING AN ELECTRIC DISCHARGE TUBE FOR VERY HIGH FREQUENCIES AND A DISCHARGE TUBE FOR USE Ill SUCH A DEVICE .Filed Jan.

JNVENTOR.

5.5. VAN IPEREN AGENT United States Patent DEVICE COMPRISING AN ELECTRIC DISCHARGE TUBE FOR VERY HIGH FREQUENCIES AND A DISCHARGE TUBE FOR USE IN SUCH A DEVICE Bernardus Bastiaan van Iperen, Eindhoven, Netherlands, assignor, by mesne assignments, to North American Philips Company, Inc, New York, N. Y., a corporation of Delaware Application January 4, 1951, Serial No. 204,328

Claims priority, application Netherlands January 19, 1950 4 Claims. (Cl. SIS-3.5)

This invention relates to a device comprising an electric discharge tube for producing electromagnetic waves of the order of 1 cm. to 1 m. The invention furthermore relates to an electric discharge tube for use in such a device.

It is known that electromagnetic waves having a length of the order of a few centimeters to a few decimeters can be produced using an electron discharge tube, in which an electron beam moves along the axis of a helical condnctor and interacts with a wave travelling along the helix. With this kind of tube it is generally difficult to maintain a particular frequency since there are various frequencies at which the electromagnetic field along the axis of the tube is sinusoidal. Moreover, these frequencies lie close together and occur at approximately the same voltage.

The object of the invention is to provide an electron discharge device capable of producing electromagnetic waves of fixed frequency in the centimeter range.

According to the invention, in a device for producing electromagnetic waves of a length of the order of 1 cm. to 1 m. and comprising an electric discharge tube, an electron beam is passed through holes in a number of substantially equispaced strips arranged transverse to the direction of motion of the electron beam and alternately connected to two conductors which extend in the direction of motion of the electron beam, the distance between the strips being such that at the particular frequency the transit time of the electrons between two successive strips is smaller than one-half cycles of the oscillation produced. Furthermore, the total length l of the oscillatory system, the wavelength A, the velocity of the electrons in volts V and the average number n of intermediate spaces between the strips on the conductors should satisfy the expression:

500 M/T O The manner of oscillation of the two conductors is such that as a whole they oscillate in phase opposition with respect to each other. The field according to the direction of motion of the electron beam is then approximately sinusoidal with a constant amplitude as a point function. It is also possible to use higher frequencies at which the field in the direction of motion of the electron beam is approximately sinusoidal, but in this case the amplitude as a point function is not constant. Moreover, the acceleration voltage associated with these frequencies is much higher, since it is proportional to together in a sectional area at right angles to the direction of motion of the electron beam. The system may either be short-circuited or not short-circuited on the side remote from the electron beam so that the Lecher wire system obtained is extended in the direction at right angles to the' currents'passing through this. The high-frequency currents passing through the system consequently move at right angles to the electron beam. In this case it is not necessary that the sectional area at right angles to the longitudinal axis of the system be rectangular, since it may take the form of a gutter-shaped or U-shaped member having a sectional area in the form of a circle sector or of dififerent form. Depending upon the presence or absence of the aforesaid short-circuit, the effective length of the Lecher wire system in a sectional area at right angles to the electron beam is an odd or an even number of quarter wavelengths. The two conductors may, alternatively, be constituted by the front and rear wall of aprismatic wave guide which may be considered to be two Lecher wire systems of one-quarter wavelength arranged with their open ends against each other.

The short-circuit in the Lecher wire system may also be constructed as to be movable outside the evacuated space of the tube, so that the tube is suitable for variable frequencies. If desired, the Lecher system may also be short-circuited within the tube to reduce parasitic radiation and to increase the natural frequency.

The invention will now be described in detail with reference to the accompanying drawing, in which:

Fig. 1 is a longitudinal section of the electrode system of a tube according to the invention; and

Fig. 2 is a cross-sectional view of the same electrode system.

Figs. 3 to 6 are cross-sectional views of variants of this electrode system; and

Fig. 7 is a perspective sketch of a resonator System of a tube according to the invention.

Referring to Figs. 1 and 2, reference numeral 1 designates an incandescent cathode and 2 an acceleration electrade which at the same time serves as a beam forming electrode. The two conductors are designated 5 and 6. The anode is designated 7. To the upper and lower walls 3 and 4 of the prismatic wave guide are secured strips 8 and 9, respectively, which are provided with recesses located behind one another for the passage of the electron beam. In this tube n=5 /2.

Strips 8 and 9 are secured to the two conductors 11 and 12 (Fig. 3) which are interconnected by a third condnctor 10, so that a gutter-shaped or U-shaped member is formed, corresponding to one-half of the prismatic wave guide shown in Figs. 1 and 2. The electrode system shown in Fig. 4 differs from that shown in Fig. 3 in that two L-shaped conductors are assembled to form a gutter-shaped member so that only a capacitative and not a conductive connection is formed in the bottom of this gutter.

Referring to Fig. 5, two conductors 16 and 17 are shunted by a movable short-circuit bridge 18 provided at the exterior of the wall 19 of the vacuum tube. The apertured elongated strips are designated 14 and 15. in order to avoid undue radiation and to increase the natural frequency, another stationary short-circuit 2i may be provided at the top of the conductors 16 and 17 (Fig. 6), whereby the tunability by means of the bridge 18 is only slightly affected.

Fig. 7 is a perspective sketch of a gutter-shaped or U-shaped member 21 of a circle-sector section, at the edges of which rings 22 and 23 are alternately arranged.

While the invention has thus been described in connection with specific embodiments thereof, other modifications will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. An electron discharge device for producing electrical oscillations having very short wavelength, said discharge device comprising an evacuated tube containing: an electron gun assembly for producing an electron beam; an anode located in the axial path of said beam; and an oscillatory electrode system interposed between said electron gun and said anode and comprising a conductive gutter-shaped U-shaped element extending parallel to said beam, said element being characterized in that each elemental cross-sectional segment thereof is tuned to the frequency of oscillation of said electron discharge device, said element having a plurality of thin conductive strip-like electrode members having a transverse cross-sectional area very substantially smaller than that of said element secured to the edges thereof, alternate striplike members extending from the opposite edges and spaced from the respective opposing edges of saidelement and spaced transversely fromthe bottom walls of said element and regularly spaced axially along said element, each of said strip-like electrode members having an aperture therethrough through which said electron beam passes one after another to excite said element into oscillation, successive ones of said strip-like members being connected to opposite edges of said element.

References Cited in the file of this patent UNITED STATES PATENTS 2,074,478 Linder Mar. 23, 1937 2,145,727 Lloyd Jan. 31, 1939 2,289,756 Clavier et al. July 14, 1942 2,289,952 Zworykin July 14, 1942 2,487,656 Kilgore Nov. 8, 1949 2,532,545 Everhart Dec. 5, 1950 2,643,353 Dewey June 23, 1953 2,653,270 Kompfner Sept. 22, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,842,704 July 8, 1958 Bernardus Bastiaan van Iperen It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 9-, strike out "gutter shaped Signed and sealed this 23rd day of September 1958.

SEAL) ttest:

KARL H. AXLINE I ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

